Palynivore

Group of herbivorous animals

In zoology, a palynivore /pəˈlɪnəvɔːɹ/, meaning "pollen eater" (from Greek παλύνω palunō, "strew, sprinkle", and Latin, vorare, meaning "to devour") is an herbivorous animal which selectively eats the nutrient rich pollen produced by angiosperms and gymnosperms. Most true palynivores are insects or mites. The category in its strictest application includes most bees, and a few kinds of wasps, as pollen is often the only solid food consumed by all life stages in these insects. However, the category can be extended to include more diverse species. For example, palynivorous mites and thrips typically feed on the liquid content of the pollen grains without actually consuming the exine, or the solid portion of the grain. Additionally, the list is expanded greatly if one takes into consideration species where either the larval or adult stage feeds on pollen, but not both. There are other wasps which are in this category, as well as many beetles, flies, butterflies, and moths. One such example of a bee species that only consumes pollen in its larval stage is the Apis mellifera carnica. There is a vast array of insects that will feed opportunistically on pollen, as will various birds, orb weaving spiders and other nectarivores. Pollen, the essential component of the palynivore diet, is a male gametophyte that is formed in the anther, or the male part of the flower. Pollen is needed to fertilize the female part of the flower, or gynoecium, and has a long history of consumption by various species. There is evidence that suggests palynivory dates back to at least the Permian period. It is likely that a coevolution has occurred between plants and palynivores in a form of mutualism, or the process by which two species individually benefit from the activity of the other. For example, palynivores benefit by receiving nutrients from the pollen, and thus the structure of the palynivore eye evolved to better interpret visual cues given by the pollen. Pollen benefits from the animal plant interaction by being spread as the animal carries it from flower to flower, furthering the reproductive success of its respective flower. Thus, pollen has evolved to be more visually appealing to palynivores, and changed its surface texture to be more readily recognized by palynivore's tactile sensory receptors. Fossil evidence from these periods suggests that early arthropods, with unspecialized mandibular mouthparts, engaged in spore feeding behavior. Within each track, further specialization of these structures has occurred. For example, in wasps and bees, eight variations of mouthpart structures incorporating glossa have been identified. The evolution of various structural and morphological adaptations of present day palynivores has also been thought to have co evolved with pollen grains. Following this period, evolution and more specialized adaptations in palynivore mouthparts and pollen or prepollen found in the gut of fossilized insects showed convergence into three major lineages: Orthoptera (grasshoppers, crickets, and locusts), Coleoptera, Diptera (flies), and Hymenoptera (wasps, sawflies, bees, and ants). To effectively collect, transport, and consume pollen, bees have evolved specialized morphological and behavioral traits. To forage for pollen, bees must first find sources of pollen, which they do so through chemical, visual, and tactile signals given by flowers Visual signals especially help guide bees to flowers. With sight adaptations such as the ability to see ultraviolet light, bees hone in on the color pattern "targets" of flower petals that guide bees to nectar and pollen. They gather and store pollen together with nectar on specialized hairs and evolved scopal or corbicular constructions on their bodies. Bees often favor certain foraging patches, In foraging, ants cannot fly to flowers to take pollen directly. As the palynivore population decreases, so do the pollination services they provide. This in turn lowers the reproductive success of flowering plants and causes an overall decline in the population of flowering plants and the number of species of flowering plants.

Palynivores can generally be grouped in two categories: specific and general. General palynivores on the other hand are adapted to consume pollen from and pollinate a wide range of different flowering plants with different flowering periods. The decline in specific palynivores can consequently lead to an increase in populations of general palynivores due to a decrease in competition and the increase in availability of resources. Depending on whether the pollinator is specific or general, the needs for the population may be different.